Mechanism for truing and dressing grinding wheels



July 7, 1925. 1,544,985

F. J. HOHNHORST ET AL MECHANISM FOR TRUING AND DRESSING GRINDING WHEELS Filed Jan. 30, 1925 2 Sheets-Sheet 1 2 Sheet -s 2 F. J. HOHNHORST ET AL MECHANISM FOR TRUING AND DRESSING GRINDING WHEELS Filed Jan:

July 7 Patented July 7, 1925.

UNITED STATES vFERDINAND J. I-IOHNHORST AN-D FERDINAND J'. KROEGER, OFCOVINGTON, KENTUCKY.

MECHANISM FOR TRUING AND DRESSING GRINDING WHEELS.

Application filed January 30, :1925. Serial No. 5,707.

To all whom it may concern:

Be it known that we, FERDINAND J. HOHN- Iioiis'r and FERDINAND J. Knononn, citizens of the United States, residing at Covington, in the county of Kenton and State of kentucky, have jointly invented certain Improvements in Mechanism for Truing and Dressing Grinding lVheels, of which the following is a specification.

()ur invention relates to mechanism for truing and dressing grinding Wheels, such as emery wheels employed in machinery for grinding or polishing surfaces of metal in precision grinding, and is exemplified as employable for truing or dressing the grinding wheel without removing the grinding whee from the grinding or polishing machine.

Our invention is an improvement upon the device shown, described and claimed in our application for patent on improvements in mechanism for truing and dressing grinding wheels, tiled in the United States Patent Otlice July 22, 1924, Serial No. T110151.

We have found that in precision grinding or polishing it is essential that the grinding Wheel shall be maintained in its true form, for instance, cylindrical form, and that for accomplishing this, it is advisable to employ a plurality of abrading wheels positioned in angular relation to each other and mounted in such manner that vibrations thereof during the grinding or polishing operation are avoided, in order tl at no grooves, ridges or varying surfaces may be imparted to the grinding or polishing surface of the grinding wheel by the truing or dressing device.

it is an object of our invention therefore to provide a truing or dressing device of this character.

it is the object of our invention further, to provide a plurality of rotary abrading parts mounted on non-parallel stubs rigidly projecting from a common rigid holder in such manner that vibrations of the axes of rotation of the rotary abrading parts are eliminated; further, to provide ball bearings for the respective rotary abrading parts at the respective sides of said rotary abrading parts whereby long bearing means extending to both sides of the respective abrading parts are provided-in order to avoid lateral wobbling of the rotary abrading parts; further, Lo provide automatic take-up means for said ball bearings, respectively having a part fixed in the direction of the axis of rotationof the rotary abrading part adjacent the inner end of the stub therein; and, further, to provide a pair of rotary abrading wheels journaled about oppositely extending stubs droopingly located on a central shank so as to locate the abrading wheels at acute angles with relation to each other below a plane in which the axis of rotation of the grinding wheel and the axis of said shank are located.

The invention will be further readily understood from the following description and claims, and from the drawings, in which latter:

Fig. 1 is a plan "iew of our improved device applied to an exemplified grinding ma chine, partly broken away.

2 is a cross-section of the same taken on the line 22 of Fig. 1, and partly broken away.

Fig. 3 is a plan view of the abrading wheels and the mounting therefor in a preferred relation to a grinding wheel, the latter partly broken away.

Fig. it is a vertical cross-section of the same, taken on the line 44 of Fig. 3, and partly broken away: and,

Fig. 5 is a detail in section on the line 55 of Fig. 2.

Ve have exemplified our invention as employed in connection with a so-called grinding or polishing machine employing a rotary grinding wheel 11 for effecting the grinding or polishing.

The work to be ground or polished, which may for instance be a shaft, is arranged to be placed between suitable centers 12, 13, of which 12 may exemplifv a head center. arranged to be rotated by suitable driving means, as by a pulley 14. A usual quill 15 in which the head-center is supported in usual manner is journaled in a bearing 16 of a headstock 17, slidable laterally on'guideways 18, 19, of a table 20.

The tail-center 11.) is mounted in a suitable sleeve 21, movable axially in a bearing 22, in usual manner, the bearing being on a tailstock 23 laterally adjustable on the guide ways 18, 19, of the table 20.

The table is exemplified as pivotally mounted by a pivot 25 on a saddle 26, which has lateral reciprocating motion imparted thereto by power means, in usual manner, as by a pinion 27, suitably driven, meshing with the rack 28 extending lengthwise of the saddle and fixed to the saddle. The saddle is slidable on guideways 29, 30, on the frame 31 of the machine.

The grinding wheel 11 is suitably fixed to a shaft 34 journaled in bearings 35 of a slide 36, adjustable toward and from the worktable on guii'leways 37, by any suitable means, the slide being arranged to be clamped by means of suitable T-bolts and nuts 38, the heads of the T-bolts coacting with the T-slot 39 in the frame, and the nuts clamping the slide to the frame. The shaft is rotatable in suitable manner, as by a belt passing about suitable pulleys it), 41, fixed to the shaft.

In the exemplitication, the work located between the centers may be caused to reciprocate axially in planes parallel to the axis of rotation of the grinding wheel for grinding or polishing straight work, or the table may be adjusted to an angle with relation to said parallelism. effected, for instance, by rotation of the handle 42 according to the reading on the gage 43.

Ne have in the present exeniplification illustrated a reciprocating table on which to mount the work, the grinding wheel, having a stationary position, although the re lation of the parts may be reversed, the work being stationarily positioned and the grinding wheel having reciprocations imparted to it. \Ve have instanced the abrading parts as acting on the grinding wheel in the absence of work between the centers. The grinding machine may be of any desirable construction.

The rotary abrading parts are exemplified as abrading wheels 45, 145. These abrading wheels are preferably of a texture much harder than the grinding wheel and of smaller diameter than the diameter of the grinding wheel on which they operate. Both abrading wheels operate on the same grinding wheel. The rotation imparted to the grinding wheel is instanced as in the direction of the arrow a, while the rotations imparted to the abrading wheels through the medium of the grinding wheel are instanced as in the directions of the arrows, b, 0.

The grinding wheel during operation becomes impregnated with particles of dirt or metal from the work being operated on, and becomes comparatively glossy and thereby loses its grinding effect, its granular structure also becoming dull at the grinding face. thereby reducing its grinding or polishing properties.

By means of our invention, particles of dirt and metal are remored from the grinding surface of the grinding wheel by coact ing rotary abrading parts which act counter to each other or crossin'gly with relation to each other upon the grinding surface of the grinding wheel, whereby to clear the recesses and pores in the grinding surface, as by having the respective abrading parts coact in different directions for drawing and wiping the particles of dirt and metal out of the recesses and pores, and for sharpening the particles or grains in the abrading surface, by successive actions thereon by the respective rotary abrading parts, effected, for instance, by the opposite positions and opposite formations of the rotary abrading arts.

By means 0 our invention further, the rotary abrading parts are mounted on rigid stubs and are caused to rotate in fixed paths for imparting regular and unvarying form to the grinding wheel throughout the grinding surface of the grinding wheel, in order that coaction between all portions of said grinding surface and the work may be equal for imparting regular and unvarying contour and polish to said Work.

The swirling actions of the respective rotary abrading parts upon the grinding surface are in opposite directions, so that the swirling action of one of said rotary abrading parts is to draw the dirt or particles of metal out of the interstices or contours in one direction, whereas the other rotary abrading part acts upon said dirt or particles in the opposite direction, so as to insure that said particles of dirt and metal are dislodged from said interstices or contours. The abrasive actions of the respective rotary abrading parts upon the particles or grains in the grinding surface are also in similar opposite directions, whereby a highly effective cleaning, abrading and sharpening action is quickly obtained.

The abrading wheels are exemplified as having their points of closest approach below their axes of rotation, the stubs on which they are mounted drooping laterally from a point preferably in the plane, exemplified by the dotted line d in Fig. 2, in which the axis of rotation of the grinding wheel and the point of intersection between the lines of contact, extended, between the abrading wheels and the grinding wheel are located, also exemplified as the plane in which the axis of rotation of the grinding wheel and the axis of the shank of our improved device are located, whiclr has the effect, as exemplified in Fig. 3, of causing the outer edges of the abrading wheels to reach under the grinding wheel to greater extent than the inner edges of said abrading wheels. when grinding or polishing said grinding wheel on a true cylinder.

The abrading wheels are normally quiescent. and rotation is imparted to them by means of the friction contact of the rotating grinding wheel therewith.

\Ve shall describe the mounting of the abrading wheel 45, the mounting of abrading Wheel 145 being similar thereto, but having the parts disposed in opposite directions, the parts being designated by similar reference numerals, but increased to the series 100.

The abrading Wheels are rotatable about stubs, shaftsor axles, preferably fixedly held to the head, and hereinafter referred to as stubs. Thus stubs 51, 151, extend in opposite directions from a central head 52, exemplified as including a bearing 53, in which the inner ends or proximate ends of the stubs are fixed. The stubs are rigid stubs, rigidly supported by the head. the stubs and head being shown as formed of separate parts rigidly connected although it is ob vious that the same may be formed integral with each other without departing from the spirit of my invention as disclosed in the appended claims.

The stub 51 is provided with an enlargement 54-, snugly fitting a bore 55 in the bearing The stub 151 is provided with a shank 56 snugly fitting a bore 57 in the enlargement 54. A pin 58, shown as a tapered pin, is driven into a hole 59 in said bearing, said enlargement and said shank, to rigidly secure said parts together. The parts are arranged to fit closely with relation to each other and are rigidly fixed with relation to each other.

The stub 51 is provided with a collar 61. It has ball bearings 62, 63, at its. respective ends, the inner raceway 64 of the ball bearing 62 being located between said collar 61 and a collar 65 rigidly secured to said stub by a pin 66.

A shell 71 is located about said stub. The outer raceway 72 of the ball bearing 63 is received in an annular groove 74 in said shell, between a shoulder 75 therein and a washer 76, the latter fixed to the end of said shell by screws 77, the wall of the aperture of said washer having close rotative connection with the collar 61 to arrest the passage of dirt and abrasive material to the interior of said shell.

A cap 81 is arranged to close the outer end of said shell, beingfixed thereto by screws 82. The outer raceway 83 of the ball bearing 63 is located in an annular groove 8-1 in said shell between a shoulder 85 thereof and said cap. The inner raceway 86 of the ball bearing 63 is received about the outer end of the stub 51.

A helical spring 87 is located between the collar 65 and the inner raceway 86. The ball bearings are combined radial and endthrust bearings. The action of the spring is to cause separating movement between the collar 65 and the inner raceway 86, thereby causing continued firm relation between the inner raceway, the balls and the outer race way of the ball bearing 68.

This causes continued outward thrust upon the shell and the outer raceway 72 of the ball bearing 62 for causing continuous firm relation between said outer raceway, the balls and the inner raceway of the ball bearing 62, the inner raceway thereof hearing continuously against the fixed collar 65. The spring resists any tendency to lateral play of the abrading wheel. This construction maintains the abrading wheel continuously in a given path of rotation and avoids lateral vibrations thereof, and at the same time permits its ready rotation.

There is a space 88 in the interior of the shell arranged to receive a lubricant through a hole 89, normally closed by a screw 90. The pins 66, 166, mav be inserted and received through said holes.

The shell has the abrading wheel fixed thereto, the abrading wheel being received in an annular rabbet 92 in the outer periphery of said shell between a shoulder 93 thereon and a nut 94 threaded to the outer threaded end 95 of said shell. Suitable "ashers 96; preferably fibrous in nature, are located between said abrading wheel, the shoulder and the nut. The threading of the threaded end is preferably in such direction as to cause tightening of the nut during operation of the abrading wheel.

Long bearings are thus provided for the abrading wheels, the ball bearings being located at the respective sides of the abradiug wheel upon a comparatively long shell whose rotative positions are fixed by the rigidly positioned stubs extending from the head.

The head is shown provided with a shank 97 extending therefrom and shown of heavy and substantial nature and arranged to be rigidly secured in place on the grinding machine. The shank is shown square in cross section in order to fix the relations between the abrading wheels and the grinding wheel, but may be of other form. 7

The exemplified means for fixing the shank in place comprise the following instrumentaliti'es: The table of the grinding or polishing machine is provided with a guide 101 and a rail 102. A clamp 103 is provided with a jaw 104 coac-ting with the guide and a clamping means comprising a iaw 196 having an inclined face it)? on the body of the clamp and a clampplate 198, the inclined face and the clamp-plate being arranged to clamp upon the rail 102.

A stem 111 is located in the bearing 112 of the clamp. An adjusting nut 115 and a lock nut 116 are received over the threaded end 117 of said stem. Said stem is provided with 'a flattened head 119, a fork 120 of a handle 121 being received about said head and articulated therewith by means of a pin 122.

The head 119 is received through a slot in a cap 126. The inner end of the fork 120 is provided with cams 129 and shoulders 130 at the respective sides of the flattened head 119. These cams and shoulders are arranged to bear against the cap, and to cause clamping movement between said cap and the clamp-plate 108 at one side of the rail 102 and the inclined face 107 at the other side of said rail, causing clamping of the jaw upon said rail.

The body of the clamp is provided with a bearing 135, shown as a clamp-bearing, in which the shank 97 is received and rigidly held, the clamp bearing being clamped to the shank by means of bolts 136, received through holes of a cheek 138 and threaded in threaded holes of a cheek 140, the cheeks being located at the respective sides of the split 141 in said clamp-bearing, which is thereby constituted a split-bearin ()ur improved device provides ready, simple, strong and accurate means for obtaining quick and effective truing, dressing, cleaning and sharpening ol' the grinding wheel in novel manner, and provides means which act with a cross-wiping motion in paths which cross each other upon the surface of the grinding wheel for cleaning, truing, dressing and sharpening the grinding surface.

hen truing or dressing a wide grinding wheel, both abrading wheels may b employed. \Vhen truing or dressing a narrow grinding wheel, a structure employing a single stub and abrading wheel may be employed, the abrading wheel rotating however in a plane at an angle to the plane of the grinding wheel. To enable this latter to be readily accomplished, the shank 97 may be round in cross-section and adjustable on its axis in the bearing 135.

Having thus fully described our invention what we claim as new, and desire to secure by Letters Patent, is:

.1. In mechanism for truing and dressing grinding wheels, the combination of a head, a pair of stubs rigid therewith extending outwardly in non-parallel directions from the respective sides of said head, a plurality of rotary abrading parts respectively rotatable about said stubs and arranged to operate on the same grinding wheel, a support, and means whereby to rigidly position said head on said support.

2. In mechanism for truing and dressing grinding wheels, the combination of a head, a pair of stubs rigid therewith extending outwardly in non-parallel directions from the respective sides of said head, a rotary abrading wheel located about each of said stubs arranged to operate on the same grinding wheel, and bearing means between each of said rotary abrading wheels and its stub extending laterally outward beyond both sides of said respective abrading wheels, said head located between said respective bearing means.

In mechanism for truing and dressing grinding wheels, the combination of a head, a pair of stubs rigid therewith extending outwardly therefrom in non-parallel directions, a shell about each of said stubs, an abrading wheel for each of said shells arranged to operate on the same grinding wheel, means for fixedly securing each of said abrading wheels to its shell, said respective shells extending outwardly laterally beyond each of the sides of said respective abrading wheels and ball bearings at the respective ends of said shell locating a ball bearing outside each side of said respective abrading wheels.

l. In mechanism for truing and dressing grinding wheels, the combination with a grinding wheel, of a head, a pair of stubs rigid therewith extending laterally outwardly therefrom in non-parallel directions, a shell about each of said stubs, a ball hearing at each end of each of: said shells, an abrading wheel fixed to each of said shells between said ball bearings at the respective ends thereof for coaction with said grinding wheel, and spring means inside said rcs 'iectivc abrading wheels between said ball bearings for each of said shells exerting end thrusts upon said ball bearings.

5. In mechanism for truing and dressing grinding wheels, the combination with a grinding wheel, of a head, a pair of stubs rigid therewith extending laterally outwardly therefrom in non-parallel directions, a shell about each of said stubs, a collar fixed in axial direction to each of said stubs inside the shell thereabout, a ball bearing at each end of each of said shells, an abrading wheel fixed to each of said shells between said ball bearings at the respective ends thereof for coaction with said grinding wheel, and spring means inside each of said shells between said collar and the ball bearing at one end thereof exerting end thrusts upon said ball bearings.

(3. In mechanism for truing and (ll'(fiiil1' grinding wheels, the combination with a grinding wheel, of a head, a pair of stubs rigid therewith extending laterally outwardly therefrom in non-parallel tlli'txlhills. a shell about each of said stubs, a eollar fixed in axial direction to each of said stubs inside the shell thereabout, a ball hearing at each end of each of said shells. an abrading wheel fixed to each of said shells llt tween said ball bearings at the respective ends thereof for coaction with said grinding wheel, and spring means inside said respective shells between said collar and said ball bearing at one end thereof exerting end thrusts upon said ball bearings, each of said shells provided with a cavity in which said respective ball bearings and spring means llt are located, and a lubricant passage and means for closing the same located inside each of said abrading wheels.

7. In mechanism for truing and dressing grin ling wheels, the combination of a head, a pair of stubs rigid therewith extending outwardly in non-parallel directions from the respective sides of said head, a plurality of rotary abrading parts respectively rotatable about said stubs in non-parallel paths arranged to operate on the same grinding wheel, a support for the grinding wheel, a support for said head, means causing reciprocation between said supports in a fixed path, and means for rigidly positioning said head with relation to said tixed path.

it. In mechanism for truing and dressing grinding wheels. the combintion of a head. a stub con'iprising an enlargement fixed in said head, said stub extending from said head in a given direction, a second stub pro vided with a shanl: lixed in said enlargement and extending from said head in opposite and non-parallel direction, a shell about each of said stubs, a hall hearing at each end of each of said shells between said respective shells and the stub therein, and an abrading wheel fixed to each of said shells between the ball bearings at the. respective ends thereof and arranged to operate on the same grinding wheel,

9. In mechanism for truing and dressing grinding wheels, the combination of a head, a shank therefor, securing means for said shank, a stub extending rigidly from said head, a shell about said stub, a normally quiescent abrading wheel secured to said shell, and ball l'iearings between said shell and said stub at the respective sides of said abrading wheel.

l0. In mechanism for truing and dressing grinding wheels, the combination of a head, a stub extending rigidly therefrom. a shell about said stub, a normally quiescent abrading wheel on said shell, and bearings be tween the respective ends of said shell and stub, said abrading wheel located between the outer ends of said bearings.

11. In mechanism for truing and dressing grinding wheels, the combination of a head, a stub extending rigidly therefrom, a shell about said stub, a normally quiescent abrading wheel on said shell, ball bearings between said shell and stub extending outwardly beyond the outer side faces of said abrading wheel, and spring means between said ball bearings inside said abrading wheel.

12. In mechanism for truing and dressing grinding wheels, the combination of a head, a pair of stubs extending in non-parallel directions at the respective sides of said head, a plurality of rotary abrading parts respectively rotatable about said stubs and arranged to operate on the same grinding wheel, a support, and means whereby to rigidly position said head on said support.

13. In mechanism for truing and dressing grinding wheels, the combination of a head, a pair of stubs extending in non-parallel directions at the respective sides of said head, a rotary abrading wheel located about each of said stubs arranged to operate on the same grinding wheel, and bearing means between each of said rotary abrading wheels and its stub extending laterally outward beyond both sides of said respective abrading wheels, said head located between said respective bearing means.

14. In mechanism for truing and dressing grinding wheels, the, combination of a head, a pair of stubs extending in non-paral el directions at the respective sides of said head, a shell about each of said stubs. an ahrading wheel for each of said shells arranged to operate on the same grinding wheel, means for fixedly securing each of said abrading wheels to its shell. said respective shells extending outwardly laterally beyond each of the sides of said respective abrading wheels, and ball bearings at the respective ends of said shell locating a ball bearing outside each side of said respective abrading wheels.

15. In mechanism for truing and dressing grii'iding wheels, the combination of a head. a shank therefor, securing means for said shank, a stub in said head, a shell about said stub, a normally quiescent abrading wheel secured to said shell. and ball bearings between said shell and said stub at the respective sides of said abradiiig wheel.

16. In mechanism for truing and dressing grinding wheels, the combination of a head. a stub therein. a shell about said stub. a normally quiescent abrading wheel on said shell, and bearings between the respective ends of said shell and said stub, said abrading wheel located between the outer ends of said bearings,

17. In mechanism for truing and dressing grinding wheels, the combination of a head, a. stub therein, a shell about said stub, a normally quiescent abrading wheel on said shell. ball bearings between said shell and said stub extending outwardly beyond the outer side faces of said abrading wheel, and spring means between said ball bearings inside said abrading wheel.

In testimony whereof we have hereunto signed our names in the presence of two subscribing witnesses.

FIIRDINAND J. HOHNHORST. FERDINAND J. KROEGER. In presence of- CLEMENT H. KROEGER, RAY H. SoHULrz. 

